You may notice that controls render on a new line when added into the RadAjaxManager settings.
This is because RadAjaxManager dynamically inserts UpdatePanels around the updated controls.
The UpdatePanel is, by default, rendered as a <div>,
which is a block-level HTML element and this causes the layout change.

RadAjaxManager exposes a property called UpdatePanelsRenderMode.
You can use UpdatePanelsRenderMode to control the render mode of the dynamically inserted UpdatePanels.

As of the Q2 2009 SP1 release of RadControls for ASP.NET AJAX, you can also define an UpdatePanelRenderMode per updated control.

Both of the above properties could be set to either Block or Inline, which will determine
whether the wrapping element will be displayed as a block or as an inline element.

When working with a RadAjaxManager, you can use the global
UpdatePanelsRenderMode property to set the render mode
for all generated UpdatePanels to inline or to block, or to set it explicitly for a particular UpdatedControl.